EP1295046B1

EP1295046B1 - Swage collar with internal sealing insert

Info

Publication number: EP1295046B1
Application number: EP01948624A
Authority: EP
Inventors: Edward E. Beeles; David Hocking; Julie R. Jones; Stuart R. Seley; John E. Inman
Original assignee: Boeing Co; Hi Shear Corp
Current assignee: Boeing Co; Hi Shear Corp
Priority date: 2000-06-23
Filing date: 2001-06-22
Publication date: 2009-04-22
Anticipated expiration: 2021-06-22
Also published as: EP1295046B2; US9027216B2; US8011076B2; AU2001270083A1; WO2002001085A1; EP1295046A1; ATE429586T1; US20120240376A1; ES2325680T3; DE60138463D1; US7597517B2; US20090320259A1; ES2325680T5; US20030219327A1

Abstract

A swage collar and an internal sealing insert form a swage collar assembly used in combination with a structural fastener to prevent leakage through a connection of workpieces fastened together by the structural fastener. The swage collar has a hollow, generally cylindrical main body portion with a main central bore, and a base portion with an internal shoulder formed in the main central bore so as to form a seal receiving guide. The shaft of the fastener typically includes a threaded section and an unthreaded section, and the internal sealing insert interfaces with the threaded section and the unthreaded section of the shaft of the pin. In an alternate embodiment, the internal sealing insert interfaces with the unthreaded section of shaft of the pin. The swage collar assembly is fitted over the fastener, a swaging tool is fitted over the swage collar assembly, and the swaging tool is forced over the swage collar assembly with sufficient force to cause plastic deformation in the swaging collar to force the swaging collar and internal sealing insert into engagement with the shaft of the fastener.

Description

BACKGROUND OF THE INVENTION:

This invention relates generally to structural fasteners, and more particularly relates to a structural fastener having a swage collar and an internal seal to prevent leakage through a connection fastened by the structural fastener.
Structural fasteners of the type to which this invention is directed typically include a headed pin with locking grooves, and a generally cylindrical collar for the pin. The structural fastener is typically used to secure a composite assembly of workpieces, and the pin is placed in aligned apertures through the workpieces to be secured together, and the collar is placed over the locking grooves of the pin. The collar is then radially compressed into the locking grooves to affix the collar on the pin. A tool that is commonly used to compress the collar over the locking grooves of the pin is a swaging tool which pulls the pin in one direction and forces a swage anvil over the collar in the other direction to affix the collar to the pin and forcibly clinch the workpieces together. When such structural fasteners are used in applications such as the joining of parts to liquid containing tanks such as aircraft fuel tanks, it is desirable that leakage from such tanks not be allowed to occur around or through such fasteners. Embodiments of the present invention can meet these and other needs.
US 3,464,472 discloses a swage type fastener comprising the features of the preamble of claim 1.

SUMMARY OF THE INVENTION

According to the present invention, there is provided a swage collar apparatus for sealing a connection of a fastener through a composite assembly of workpieces together and for preventing leakage through the connection, the fastener including a shaft having an externally threaded or grooved section, the swage collar apparatus comprising a hollow, generally cylindrical swage collar adapted to be disposed over the shaft of the fastener, the swage collar having a main body portion with a main central bore, and a base portion with an internal shoulder formed in the main central bore so as to form a seal receiving guide, the internal shoulder having a diameter that is larger than the diameter of the main central bore, and an internal sealing material disposed in the swage collar over the fastener, characterized in that: the internal sealing material comprises an internal sealing insert having a surface defining an annular rounded exterior flange, and the internal shoulder of the main central bore of the swage collar has a surface defining a corresponding rounded channel or groove into which the annular rounded exterior flange interfits, to thereby lock the internal sealing insert into place within the internal shoulder of the main central bore.
There is also provided the method of claim 13.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a sectional view of an assembly according to a first embodiment, showing a portion of a pin with the swaging collar and internal sealing insert;
Figure 2 is a sectional view of an assembly according to a second embodiment, showing a portion of a pin with the swaging collar and internal sealing insert;
Figure 4B is a plan view of the swaging tool;
Figure 4C is a sectional view of the swaging tool taken along line 4C-4C of Figure 4B;
Figure 4D is a sectional view of an alternate embodiment of a swaging tool;
Figure 4E is an end view of the swaging tool of Figure 4D;
Figure 5A is a schematic diagram showing the slicing off of a portion of a metal wire or bar stock to form a blank for the formation of the swaging collar, according to the present invention;
Figure 5B is a schematic diagram illustrating the punching of the blank of Figure 5A for form indentations in the blank;
Figure 5C is a schematic diagram illustrating the forcing of the punched blank into a die by another punch to form the swaging collar according to the present invention;
Figure 6A is a sectional view of a swaging collar and a sealing insert assembly showing the dimensions of the sealing insert in relation to the collar;
Figure 6B is a sectional view of a swaging collar showing the dimensions of the collar;
Figure 6C is a sectional view of an alternate embodiment of a blank for the formation of the swaging collar;
Figure 7A is a partially exploded perspective view of a swaging tool assembly;
Figure 7B is a perspective view of the assembled swaging tool of Figure 7A;
Figure 7C is an end view of the assembled swaging tool of Figure 7B;
Figure 7D is a sectional view of the swaging tool assembly taken along line 7D-7D of Figure 7C;
Figure 8 is a sectional view of an embodiment of a swaging collar and a sealing insert in an uninstalled and unswaged condition apart from the pin, according to the present invention; and
Figure 9 is a detail view of the circled portion of Figure 8.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In Figures 1 and 2, a hollow, generally cylindrical swage or swaging collar 3 with an internal sealing insert 5 is shown. The swaging collar includes a main body portion 1 with a main central bore 2, and a base portion 4 with an internal shoulder 6 formed in the main central bore so as to form a seal receiving guide. The internal shoulder has a diameter that is larger than the diameter of the main central bore. The base portion is preferably flared outward, and has an external diameter larger than the main body portion. The swage collar and seal are intended for use with an externally threaded fastener such as a pin 7 having a shaft 8 and an enlarged head 9, the pin being of the type used in fastening together components11 in aerospace and other applications.
Figure 1 depicts an assembly in which the relative dimensions of the pin 7, its threads or grooves 10, the swage or swaging collar 3, and the internal sealing insert 5 are such that the sealing insert interfaces with a relatively flat, unthreaded, ungrooved section 12 of the pin. Figure 2 depicts an assembly in which the relative dimensions of the pin 7, its threads or grooves 10, the swaging collar 3, and the internal sealing insert 5 are such that the sealing insert interfaces with a threaded or grooved section 15 of the pin. Although either configuration may provide a useful fastener, the configuration of Figure 2 provides greater grip and more secure sealing and is therefore regarded as preferable.

The collar is made of a suitable metal or another deformable material. Applicants have used aluminum (2024 Aluminum per QQ-A-430 or AMS-QQ-225/6), with heat treatment to a T4 or T42 condition per AMS2770 or AMS-H-6088), and commercially pure titanium (CP Titanium per ASTM B348 Grade 1, MIL-T-9047 CP-4). Applicants have used tetrafluoroethylene (TFE), such as TFE available under the brand name "TEFLON" from DuPont, per ASTM D1710 Type I, Grade 1 for the sealing insert. Other materials may be specified for either the collar 3 or the sealing insert 5 based on desired material properties well known to those skilled in the art. Exemplary dimensions for the swaging collar and sealing insert are presented in Table 1 below. In the tables below, "Dash No." indicates the nominal diameter of a mating pin in 1/32nds of an inch. The dimensions apply after the swaging collar and sealing insert are finished.

Table 1. Dimensions of the swaging collar and sealing insert

Dash	Pin	A	B	C	E	F	J	L	M	N	P
No.	Nom.	Dia.	Dia.	Dia.	Dia.	Dia.	RAD		Max.	REF.	Max
	Dia.			Min.	Min.		REF.
6	3/16	.384	.193	.188	.185	.298	.150	.284	.055	.060	.016
		.364	.189			.294		.264
8	1/4	.477	.253	.248	.245	.391	.150	.349	.070	.060	.016
		.457	.249			.387		.329
10	5/16	.581	.316	.310	.310	.484	TBD	.448	TBD	.060	.031
		.561	.312			.480		.428
12	3/8	.712	.378	.372	.372	.588	TBD	.493	TBD	.060	.031
		.692	.374			.584		.473

The collar assembly 18, comprising the swaging collar 3 and the sealing insert 5, is installed using a swaging tool 20 depicted in Figures 4B-4E. The collar assembly may have a wide range of dimensions. Each collar assembly will be installed with an appropriately sized matching swaging tool.
Referring now especially to the cross-sectional detail view of Figure 4C, the swaging tool 20 defines a collar entrance aperture 23 at one end. A transverse aperture 24 is provided through the body of the swaging tool for a dowel pin 26 shown in Figure 7A. The tool is sized so that the entrance aperture has an inside diameter at its edge 25 that is slightly larger than the outside diameter of the swaging collar at the swaging collar's outside edge 27. The swaging tool may thus be fit over the swaging collar. The interior 30 of the swaging tool necks down smoothly to a relatively narrow point 32 on the swaging tool where the inside diameter is slightly smaller than the outside.
To swage the collar assembly 18 onto a threaded pin 7, the collar assembly is first fitted over the pin. The relative clearances between the pin and the sealing element and swaging collar are such that this may be done by an assembler by hand. The swaging tool 20 is then fit over the swaging collar and forced over the collar by a pneumatic impact tool or another appropriate means. Sufficient force is applied to the swaging collar to cause plastic deformation in the swaging collar so that the material of the swaging collar is force into the threads, thereby bringing the sealing element into tight sealing engagement with the pin as shown, e.g., in Figures 1 and 2.
A swaging collar assembly incorporating the invention has been found to be particularly useful in applications such as the joining of parts to aircraft fuel tanks. The combination of the threaded pin and metal swaging collar provide an inexpensive, easily installed, and secure fastener for joining the parts together, while the presence of the sealing element and its engagement with the pin prevent leakage of fuel or other fluids from the tank.
The swaging collar may be formed by conventional machining technique such as turning on a lathe. It has been found more economical, though, to form the swaging collar 3 by a technique illustrated in Figures 5A-5C. As indicated in Figure 5A, the process begins with a length of metal wire or bar stock 35. A forming blank 38, having a volume equal to the final volume of the swaging collar, is sliced off the end of the stock.
Moving now to Figure 5B, the forming blank 3 8 is punched at both ends to form twin indentations 40 in the cylindrical blank. Finally, as indicated in Figure 5C, the punched blank 43 is forced into a die 45 by another punch 47. The punch goes entirely through the blank, forming an opening through it while forcing it against the sides of the die. A step 50 on the punch forms a well 52, into which the sealing insert 5 is set before the collar assembly 18 is swaged onto the pin.

Figures 6A-B show views and dimensions of a collar and insert assembly with exemplary dimensions presented in Table 2 below. Figure 6C shows an alternate embodiment of a preform blank 43' of the collar with the blank formed with an opening entirely through the blank, for

dash no. sizes

10 and 12, with exemplary dimensions presented in Table 3 below. Figures 7A-D show views of a swaging tool assembly 60, which includes an anvil 62, ball bearings 64 at a top end 65 of the anvil, a nut 66 over the ball bearings at the top end of the anvil, and over a snap ring 68 located in a groove 70 at a mid-portion of the anvil. A sleeve 72 is provided over and threadedly connected to the nut, extending to the bottom end 73 of the anvil.

Table 2. Dimensions of the swaging collar and sealing insert (†- To be determined)

Dash	A	B	E	F	H	J	L	N	P	X	AB	AD
No.	Dia.	Dia.	Dia.	Dia.	Dia.	Rad			Max		Dia.
			Min								Min.
5	.346	†	.160	.260	.167	†	.266	.065	.016	.060	.164	†
	.326			.256	.163		.246	.055		.055
6	.384	†	.185	.298	.193	†	.284	.065	.016	.060	.188	†
	.364			.294	.189		.264	.055		.055
8	.477	.325	.245	.391	.253	.160	.349	.060	.016	.060	.248	.055
	.457	.323		.387	.249	.150	.329	.055		.055		.040
10	.581	†	.310	.484	.316	†	.448	.060	.031	.060	.310	†
	.561			.480	.312		.428	.055		.055
12	.712	†	.372	.588	.378	†	.493	.060	.031	.060	.372	†
	.692			.584	.374		.473	.055		.055

Table 3. Dimensions of the preform blank

Dash	BA	BH	BL	BR
No.	Dia.	Dia.		Rad.
10	.569	.320	TBD	.040
	.567	.318		.030
12	.700	.382	TBD	.040
	.698	.380		.030

Figures 8 and 9 depict an embodiment of a swaging collar 83 and a sealing insert or sealing ring 85 in an uninstalled and unswaged condition apart from the pin (not shown). The swaging collar includes a main body portion 81 with a main central bore 82, and a base portion 84 with an internal shoulder 86 formed in the main central bore so as to form a seal receiving guide. The internal shoulder has an interior diameter that is larger than the diameter of the main central bore. The base portion is preferably flared outward, and has an external diameter larger than the main body portion. The swage collar and seal are intended for use with an externally threaded or grooved fastener such as a pin having a shaft and an enlarged head, the pin being of the type used in fastening together components in aerospace and other applications, as described above. The collar is made of a suitable metal or another deformable material, such as commercially pure titanium or aluminum, as described above. The sealing insert may also be made of tetrafluoroethylene (TFE), such as TFE available under the brand name "TEFLON" from DuPont, as described above. Other materials may be specified for either the collar 83 or the sealing insert 85 based on desired material properties well known to those skilled in the art. The sealing insert includes an annular rounded exterior flange 87, that interfits into a corresponding rounded channel or groove 89 in the internal shoulder of the main central bore, in order to lock the sealing insert into place within the internal shoulder portion of the main central bore. The internal shoulder of the main central bore may also include an intermediate stepped portion 90 with an interior diameter that is less than the interior diameter of the internal shoulder 86 and greater than the diameter of the main central bore, in order to further lock the sealing insert into place in the internal shoulder of the main central bore.

Claims

A swage collar apparatus for sealing a connection of a fastener (7) through a composite assembly of workpieces (11) together and for preventing leakage through the connection, the fastener (7) including a shaft (8) having an externally threaded or grooved section (10), the swage collar apparatus comprising a hollow, generally cylindrical swage collar (3) adapted to be disposed over the shaft (8) of the fastener (7), the swage collar (3) having a main body portion (1) with a main central bore (2), and a base portion (4) with an internal shoulder (6) formed in the main central bore so as to form a seal receiving guide, the internal shoulder (6) having a diameter that is larger than the diameter of the main central bore, and an internal sealing material (5) disposed in the swage collar (3) over the fastener (7), characterized in that:
the internal sealing material comprises an internal sealing insert (5, 85) having a surface defining an annular rounded exterior flange (87), and the internal shoulder (6, 86) of the main central bore (2, 82) of the swage collar (3, 83) has a surface defining a corresponding rounded channel or groove (89) into which the annular rounded exterior flange (87) interfits, to thereby lock the internal sealing insert (5, 85) into place within the internal shoulder (6, 86) of the main central bore (2, 82).
The swage collar apparatus of Claim 1, wherein the base portion (4, 84) is flared outward, having an external diameter larger than the main central bore (2, 82).
The swage collar apparatus of Claim 1, wherein the swage collar (3, 83) is made of a metal.
The swage collar apparatus of Claim 3, wherein the swage collar (3, 83) is made of aluminum.
The swage collar apparatus of Claim 3, wherein the swage collar (3, 83) is made of titanium.
The swage collar apparatus of Claim 1, wherein the swage collar (3, 83) is made of a deformable material.
The swage collar apparatus of Claim 1, wherein the internal sealing insert (5, 85) is made of tetrafluoroethylene.
The swage collar apparatus of Claim 1, wherein the shaft (8) includes an unthreaded section (12), and the internal sealing insert (5, 85) interfaces with the unthreaded section of shaft (8) of the pin.
The swage collar apparatus of Claim 1, wherein the shaft (8) includes a threaded section (10) and an unthreaded section(12), and the internal sealing insert (5, 85) interfaces with the threaded section and the unthreaded section of the shaft (8) of the pin.
The swage collar apparatus of Claim 1, wherein the internal shoulder (6, 86) of the main central bore (2, 82) includes an intermediate stepped portion (90) having an interior diameter that is less than the interior diameter of the internal shoulder (6, 86) and greater than the diameter of the main central bore (2, 82).
The swage collar apparatus of Claim 1, further including a fastener (7) comprising a pin (7) having a head (9) and a shaft (8), the shaft (8) having an externally threaded section (10) and an unthreaded section (12).
The swage collar apparatus of Claim 11, further including a swage tool (60) which mechanically forces the swage collar (3, 83) over the pin affixing a workpiece between the enlarged head and the swage collar (3, 83) with the internal sealing insert (5, 85) deforming and forming a fluid impermeable seal.
A method of installing a sealing fastener (7), the sealing fastener (7) including a fastener (7) having a shaft (8), a swage collar assembly including a swage collar (3, 83) and an internal sealing insert (5, 85) according to Claim 1, comprising:
fitting the swage collar assembly over the fastener (7);

fitting a swage tool (60) over the swage collar assembly, the swage tool (60) having a collar entrance aperture (23) at one end, the collar entrance aperture (23) having an inside diameter at an inside edge (25) that is slightly larger than the outside diameter of the swage collar (3, 83) at the outside edge (27) of the swage collar (3, 83), so as to fit over the swage collar (3, 83); and

forcing the swage tool (60) over the swage collar assembly with sufficient force to cause plastic deformation in the swage collar (3, 83) so that the material of the swage collar (3, 83) is forced into engagement with the shaft (8) of the fastener (7), and to bring the internal sealing insert (5, 85) into sealing engagement with the shaft (8) of the fastener (7) to form a fluid impermeable seal to prevent leakage through a connection formed by the fastener (7) through the composite assembly of workpieces (11).